(loosely) A contradiction in terms. Historically, an oxymoron was a paradox with a point, where the contradiction seems absurd at first glance, and yet is deliberate, its purpose being to underscore a point or to draw attention to a concealed point.
By far the most massive planet in our solar system, Jupiter features giant hurricanes, auroras, abstract artistic cloudswirls, and maybe even a solid core. It also protects Earth by gravitationally clearing the solar system of asteroids and comets.
Jupiter is around five times less dense than Earth, so an Earth the size of Jupiter would have tremendous surface gravity, would generate a very large amount of geothermal energy. From calculations based on the compressibility of rock, Earth would settle at 4 times the radius, so 16 times more surface for people to live on.